JP2010514322A - Multi-beam transmission separation - Google Patents

Abstract

  A method for separating an ultrasound transmit beam and reducing cross transmit beam interference in a multi-beam system transmits a first ultrasound beam at first and second positive angles, the first and second Transmitting the second ultrasound beam at a negative angle of. The method further includes receiving first, second, third and fourth composite signals, each of the composite signals including a return signal and a reflected component. The method further includes applying a first and third finite impulse response filters to obtain an average of the first and second composite signals and an average of the second and fourth composite signals to remove reflected components. And applying to the second and fourth composite signals.

Description

  The present invention generally relates to ultrasonic imaging using a plurality of ultrasonic transmission beams, and more particularly to separation of ultrasonic transmission beams and reduction of cross transmission beam interference in a multi-beam system using a Doppler method.

  The ultrasonic diagnostic method is one of the most versatile and cheapest, and is widely used as a diagnostic imaging modality used today. With the advent of 3D ultrasound and Doppler tissue imaging (DTI), much effort has been expended to increase the frame rate in ultrasound imaging. One particular method involves receive multiline beam processing where a number of ultrasound receive beams are calculated for each transmit beam or event.

  The problem with this method is that in order to receive energy along a given scan line direction, ultrasonic transmission energy needs to be supplied along that line of sight. There are basically two approaches to solving this problem.

  The first approach involves expanding or “fatting” the transmit beam to encompass a larger area or volume. This technique reduces resolution (both detail and contrast) and reduces sensitivity.

  The second approach involves simultaneously transmitting or “firing” multiple focused and compact transmit beams to the human body. The problem with this method is cross transmit beam interference (ie, the occurrence of crosstalk), that is, the energy from one transmit beam contaminates the receive beam collected along the other transmit beam (and vice versa). the same).

  Several solutions have been shown to solve this problem of cross transmit beam interference. Some of these solutions actively disable receive beamforming to eliminate energy from other transmit beams, encoded excitation, spatial diversity (ie keep the transmit beam as far apart as possible) Placement), and frequency diversity. For example, U.S. Pat.No. 6,179,780 is intended to overcome crosstalk problems, including using receive beam synthesizers, using encoded transmissions, using non-uniform scan sequences, and using different transmit center frequencies. Various methods are described. To the best of the inventors' knowledge, these methods are not currently commercially available.

  The present invention provides a solution to cross-transmit beam interference in a multi-beam system by providing a novel method for separating energy from a desired transmit beam and means for reducing energy and sensitivity to “other” transmit beams. provide.

  The method of the present invention for separating ultrasound transmit beams and reducing cross transmit beam interference in a multi-beam system includes first transmitting at least two of the ultrasound beams at independent spatial locations. Each transmitted ultrasonic beam generates an echo return, generates a sequence of transmitted events, applies a phase factor to each transmitted ultrasonic beam in each transmitted event, At each successive transmission event, the phase coefficient is modulated by a unique amount for each transmitted ultrasonic beam, and the remaining transmitted signals are constructively added with the energy from the desired transmitted ultrasonic beam. Linearize echo returns from two or more transmitted events by disrupting the energy from the ultrasound beam Including the step of forming.

  The above and other objects, aspects, features and advantages of the present invention will become apparent from the following description and from the claims.

  The invention will be further described in the following detailed description with reference to the drawings by way of non-limiting illustrated embodiments of the invention. However, it should be understood that the invention is not limited to the precise arrangements and instrumentalities shown. In the drawings, like reference characters generally refer to the same parts throughout the different views. In addition, these drawings are not shown to scale, and instead, portions that explain the principles of the present invention are highlighted.

1 is a schematic diagram illustrating an ultrasonic beam transmitter arranged for scanning human tissue according to one embodiment of the present invention. FIG. 1 is a schematic diagram illustrating receive and transmit beams according to one embodiment of the invention. FIG. 4 is a schematic diagram illustrating receive and transmit beams according to another embodiment of the present invention. FIG. 4 is a schematic diagram illustrating receive and transmit beams according to another embodiment of the present invention. 4 is a table illustrating ultrasound transmission events, angles and polarities according to one embodiment of the invention. 6 is a flow chart illustrating a method for reducing transmitted transmit beam interference by separating transmitted ultrasound beams in a multi-beam system according to an embodiment of the present invention. Schematic illustrating four simultaneous transmit beams in the same plane for scanning a two-dimensional image. Schematic illustrating four simultaneous transmit beams that are not in the same plane for scanning a volume. The figure which shows the transmission waveform sequence in case a transmission waveform is the same. The figure which shows the transmission waveform sequence in case a polarity switches for every transmission. The figure which shows the transmission waveform sequence in case a transmission waveform uses a traveling phase term. The figure which shows the transmission waveform sequence in case a transmission waveform uses a delay phase term. FIG. 4 is a schematic diagram illustrating receive and transmit beams according to another embodiment of the present invention. Schematic illustrating different transmitted wave fields transmitting sound waves into the body. Schematic illustrating the addition of patch echoes returning from the body.

  Reference will now be made in detail to the preferred embodiments of the present invention. While the invention will be described in conjunction with the preferred embodiments, it will be understood that they are not intended to limit the invention to these embodiments. On the contrary, the invention is intended to cover alternatives, modifications and equivalents that may be included within the spirit and scope of the invention as defined by the claims of this specification. Is. Furthermore, in the following detailed description of the present invention, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be recognized by one skilled in the art that the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, components, and circuits have been described in detail so as not to unnecessarily obscure aspects of the present invention.

  Referring to FIG. 1, in a simple embodiment, two simultaneous ultrasound transmit beams are used for each scan frame or scan volume, and in other embodiments, as described below, More simultaneous ultrasonic transmission beams are used. FIG. 1 shows an ultrasound transceiver 102 with thick solid arrows 106, 112 corresponding to two simultaneous transmit beams arranged to scan human tissue. Solid lines 104, 120, 122, 124 surrounding these thick lines with arrows 106, 112 indicate an energy beam width of about 6 dB, effectively defining the width (resolution) of the transmitted beam corresponding to its axial depth. By using dynamic receive beamforming, four simultaneous receive beams 108, 110, 114, 116 indicated by the dotted arrows are acquired. FIG. 1 includes two receive beams 114, 116, 108, 110 for each transmit beam 106, 112. Multiple simultaneous transmission events are activated to scan the entire two-dimensional image, or in the case of a volume, to scan both the lateral and elevation dimensions of the volume. The ultrasonic transmitter 102 generates one ultrasonic beam 106 at a positive 45 ° angle and another ultrasonic beam 112 at a negative 45 ° angle.

  By using dynamic receive beamforming, receive beams 108 and 114 are acquired or received by the ultrasound transceiver 102. However, the receiver 102 further receives a beam or signal 116 that is a reflected component of the return beam or signal 114. Signal 116 contaminates the return beam or signal 108. Similarly, the receiver 102 further receives a beam or signal 110 that is a reflected component of the return signal 108. Signal 110 contaminates return signal 114. This cross-contamination of the return signals 108 and 114 is called cross-transmit beam interference and reduces the contrast resolution of the ultrasound image.

To remove the contamination signals 114 and 116 from the return signals 108 and 110, respectively, a two coefficient finite image response (FIR) is applied to each of the return signals 108, 110, 114, 116 according to equations A and B shown below. Applied.
Formula A: ((B3 + N1) + (B4 + (-N2))) / 2 = ((B3 + B4) / 2) + ((N1-N2) / 2) = average of B3 and B4 Formula B: ((B1 + N3)-(((-B2) + N4)) / 2 = ((B1--B2) / 2)-((N3-N4) / 2) = average of B1 and B2

  Here, B1, B2, B3, and B4 are transmission beams, and N1, N2, N3, and N4 are nodes.

In a simple embodiment as shown in FIG. 1, it is possible to assume two receive beams or signals per transmit beam and further assume that the receive beams overlap because the transmit beam sequence occurs over the entire field of view. Can do. The following simple table shows the sequence of a simple embodiment.

  FIG. 2A corresponds to this simple table and shows a simple embodiment of the present invention. FIG. 2A shows a solid line down arrow corresponding to the transmit beams 150, 160 and a dotted line up arrow corresponding to the receive beam positions 165, 168. It is assumed that the left transmission event 150 switches polarity, while the right transmission event 160 maintains the same polarity.

And in this simple embodiment, there is a round trip reconstructed beam only at odd degree values (corresponding to the table in the above example). Focusing only on “good” or uncontaminated energy intensifying interference, the following equation is generated:
RT _-43 = (+ R _-43 X _-44 --R _-43 X _-42 ) / 2
RT _-41 = (-R _-41 X _-42- + R _-41 X _-40 ) / 2
RT _-39 = (+ R _-39 X _-40 --R _-39 X _-38 ) / 2

RT _-43 is the reciprocating beam position at -43 °.

R _-43 X _-44 is the receive beam at -43 ° with respect to the transmit beam at -44 °.

At the same time, solving for the round trip related to the transmission beam "B"
RT ₁ = (+ R ₁ X ₀ + + R ₁ X ₂ ) / 2
RT ₃ = (+ R ₃ X ₂ + + R ₃ X ₄ ) / 2
RT ₅ = (+ R ₅ X ₄ + + R ₅ X ₆ ) / 2

It should be noted that the desired energy associated with RT- ₄₃ has a transmission that switches in polarity every other transmit beam (+,-, +,-). Therefore, the “minus” sign is in the expression. Conversely, the code for coherently adding energy for RT ₁ is always associated with a transmit beam that is the same polarity. Therefore, coherent sums require that the received beams be “summed”.

The above formula actually occurs because a negative power round trip beam (eg RT- ₄₃ ) is also susceptible to “bad” or contaminated energy from positive power transmission events (and vice versa) It is an oversimplification of what it does. The following equation includes the effects of “bad” energy.
RT _-43 = {(+ R _-43 X _-44 + _BAD R _-43 X ₁ )-(-R _-43 X _-42 + _BAD R _-43 X ₃ )} / 2

Rearranging the terms in this formula gives the following formula.
RT _-43 = {(+ R _-43 X _-44 + R _-43 X ₁ ) + ( _BAD R _-43 X ₁ - _BAD R _-43 X ₃ )} / 2

  The desired good energy in the first half of this equation is added coherently, while the “bad” energy from the second half of the equation is properly destroyed. This is easily seen for other “negative” angles.

The technique represented by the above equation is also effective for positive reciprocating angles, as will be shown below.
RT ₁ = {(+ R ₁ X ₀ + _BAD R ₁ X _-44 ) + (+ R ₁ X ₂ - _BAD R ₁ X _-42 )} / 2

Rearranging the terms in this formula gives the following formula.
RT ₁ = {(+ R ₁ X ₀ + R ₁ X ₂ ) + ( _BAD R ₁ X _-44 - _BAD R ₁ X _-42 )} / 2

  Similarly, it can be seen that the bad energy from the opposing transmit beams is properly offset.

  In a more advanced preferred embodiment, there are a large number of receive beams for each transmit event, and in the case of simple positive / negative polarity, the spans of the receive beams overlap each other by 50 percent. FIG. 2B shows four receive beams per transmit beam, and the receive beam spans overlap each other by 50 percent. In FIG. 2B, as shown in FIG. 2A, the solid line downward arrow corresponds to the transmit beams 210 and 220, and the dotted line upward arrow corresponds to the receive beam positions 230 and 240. Similar to the simple embodiment described above, it is assumed that the polarity is switched in the left transmission event 210 and the same polarity is maintained in the right transmission event 240.

  In the example illustrated in FIG. 2B, “interpolating” the correct round beam position requires the use of factors such as 1/4, 3/4, which results in a “good” energy correct placement. However, since the “bad” energy is only reduced by 6 dB (1/2), the cross-beam rejection is reduced.

In the preferred embodiment, there are 8 or more receive beams per transmit beam and the overlap is greater than 75 percent. This is shown in FIG. 2C. Circled regions 250, 260 show how the round trip beam is reconstructed from the same angled receive beam corresponding to four different transmit events 212. Since the round-trip beam has four different coefficients associated with it (ie, a 4-tap interpolation filter), the ability to suppress “bad” energy from other transmit beams is improved. The formulas that determine how the group 250 receive beams are combined are:
RT ₂₅₀ = a * X ₁ R ₇ -b * X ₂ R ₅ + c * X ₃ R ₃ -d * X ₄ R ₁

  There are several constraints on the coefficients that should improve performance and achieve the desired result.

Constraint # 1: The sum of coefficients must be equal to 1.
a + b + c + d = 1
As a result, the average energy of the plurality of reception beams has a gain of 1.

Constraint # 2: The coefficient must be interpolated at a position between X2 and X3 transmit beams, and in particular, closer to X2 (as illustrated in FIG. 2C). If this is described by an expression,
1 * a + 2 * b + 3 * c + 4 * d = 2.25
It becomes. Note that 1,2,3,4 correspond to the spatial positions of the transmit beams X1, X2, X3 and X4, and the value 2.25 corresponds to the desired position of the interpolated output.

Constraint # 3: The coefficient needs to cancel the energy from the transmit beam where the polarity of group 260 in FIG. 2C is not switched. This can be achieved by switching the polarities of the coefficients so that their sum is zero.
a-b + c-d = 0
One solution that satisfies the above constraints is
a = 0.025
b = 0.60
c = 0.475
d = -0.10
It is.

For the group of receive lines defined by 255 (on the right side of group 250), the coefficients can be exchanged and
RT ₂₅₅ = d * X ₁ R ₇ -c * X ₂ R ₅ + b * X ₃ R ₃ -a * X ₄ R ₁
It becomes.

  Note that the exchange of coefficients changes constraint # 2 and the resulting output beam is interpolated to "2.75" (still between X2 and X3, but this time closer to X3).

Similarly, these coefficients can be applied to groups 260 and 265 (to the right of 260).
RT ₂₆₀ = a * X ₁₀₁ R ₇ + b * X ₁₀₂ R ₅ + c * X ₁₀₃ R ₃ + d * X ₁₀₄ R ₁
RT ₂₆₅ = d * X ₁₀₁ R ₇ + c * X ₁₀₂ R ₅ + b * X ₁₀₃ R ₃ + a * X ₁₀₄ R ₁

  Note the difference in the sign of the coefficients.

  As will be apparent to those skilled in the art, the round trip beams defined by RT 250, RT 255, RT 260 and RT 265 are accurately positioned to reject leakage energy from “other” groups of transmit beams.

A further embodiment of the present invention is its use in conjunction with US Provisional Patent Application No. 60 / 747,148 (Title of Invention "ULTRASONIC SYNTHETIC TRANSMIT FOCUSING WITH A MULTILINE BEAMFORMER") incorporated herein by reference. . In this case, the RT260 reciprocating beam can be described as follows:
_{RT 260 (t) = a *} X 1 R 7 (td 1) + b * X 2 R 5 (td 2) + c * X 3 R 3 (td 3) + d * X 4 R 1 (td 4)

In this equation, “t” refers to the time that the ultrasound echo arrives from the increasing depth in the body, and the delays d1, d2, d3, d4 are the transmission beams in the past as defined in the above provisional patent application. Calculated to retroactively beam form. By applying constraint # 3 (a-b + cd = 0 ) of the above RT ₂₆₀ (t) equation, it is possible to achieve energy relief from income and undesired transmission beam of the improved transmission focusing .

  Referring to FIG. 3, a table of ultrasound transmission events 301 (instances of transmitted signals) including transmission angles 302, 304 and transmitted signal polarities 306, 308 in one embodiment is shown. With respect to the transmitter 204, the transmission angle 302 is incremented by + 2 ° from −45 ° to −1 °, and the polarity 304 of the transmitted signal remains positive (in phase). For transmitter 202, the transmission angle 306 is incremented by 2 ° from + 1 ° to + 45 °, and every other signal transmission is transmitted 180 degrees out of phase with the previous signal transmission. The signal polarity 308 switches from positive to negative (180 ° out of phase).

  With reference to FIGS. 3 and 4, the method described above is repeated for each pair of consecutive transmit beams at each transmitter 202 and 204. For example, the transceiver 202 transmits the beam 206a at an angle of + 1 °, while the transmitter 204 transmits the beam 212a at an angle of −45 ° (step 402). Receiver 220 receives return signal 208a and reflected signal 216a, and receiver 222 receives return signal 214a and reflected signal 210a (step 404). Transmitter 202 then transmits beam 206b at an angle of + 3 °, while transmitter 204 transmits beam 212b at an angle of −43 ° (step 406). Receiver 220 receives return signal 208b and reflected signal 216b, and receiver 222 receives return signal 214b and reflected signal 210b (step 408). The data processing unit (eg, computer) executes an average signal calculation algorithm to determine the average of the return signals 208a and 208b and the return signals 214a and 214b (step 410).

  Next, transmitter 202 transmits a third beam at an angle of + 5 °, while transmitter 204 transmits a third beam at an angle of −41 ° (step 412). Receiver 220 receives the third return signal and the third reflected signal, and receiver 222 also receives the third return signal and the third reflected signal (step 414). The data processing unit again executes the signal average calculation algorithm to determine the average of the return signal 208b and the third return signal and the average of the return signal 214b and the other third return signal (step 412). ). This sequence of steps is repeated until the desired tissue region (not shown) is scanned.

  All of the above embodiments involve two simultaneous transmit beams, one sequence of beams maintains normal polarity, and the second set of transmit beams switches polarity. Aspects of the present invention support more than two transmit beams, and energy from all other transmissions is reduced for any given transmit beam sequence. The following example shows four beam sequences that are simultaneous. The four simultaneous transmit beams 510 can be coplanar to scan a two-dimensional image, as illustrated in FIG. 5A, or to scan a volume, as illustrated in FIG. 5B. They may not be in the same plane (520). To transmit a non-planar transmit beam, a two-dimensional matrix transducer 530 of elements is used, as shown in FIG. The following example applies to both planar and non-planar cases. The elimination of bad energy is done in the time domain, and it does not matter where in the space the cross-contaminated transmit beam is located.

  In one embodiment, assume there are four beam sequences called Xa, Xb, Xc and Xd. Each beam covers a different part of the scanned area. In addition, each beam travels with four different transmit waveforms.

In Xa shown in FIG. 6A, the transmission waveform is the same. These can be expressed as follows:
Xa (t, n = 1) = cos (2 * pi * f * t) * w (t)
Xa (t, n = 2) = cos (2 * pi * f * t) * w (t)
Xa (t, n = 3) = cos (2 * pi * f * t) * w (t)
Xa (t, n = 4) = cos (2 * pi * f * t) * w (t)

  Note that “t” refers to time, “n” refers to a transmission event, “f” refers to a nominal transmission frequency (eg, 5.0 MHz), and “w (t)” refers to a time windowing function. . For the embodiments of FIGS. 6a, 6b, 6c and 6d, w (t) can be a rectangular windowing function that is on (= 1) only between −0.4 and +0.4 usec. At 5MHz this results in a transmit waveform with only 4 cycles. It is assumed that w (t) is the same for all transmission sequences (Xa, Xb, Xc and Xd). Further, the four waveform sequences are repeated, and it is assumed that the fifth waveform uses waveform # 1 (Xa (t, n = 5) = Xa (t, n = 1)).

For the Xb shown in FIG. 6B, the transmission waveform uses the above-described method in which the polarity is switched every other transmission. This can be expressed as:
Xb (t, n = 1) = + cos (2 * pi * f * t) * w (t)
Xb (t, n = 2) =-cos (2 * pi * f * t) * w (t)
Xb (t, n = 3) = + cos (2 * pi * f * t) * w (t)
Xb (t, n = 4) =-cos (2 * pi * f * t) * w (t)

However, Xc (and Xd) requires yet another sequence that can be uniquely distinguished. In this case, the phase of the transmission waveform can be advanced (or delayed). Xc using the term that advances the phase can be expressed as follows, as shown in FIG. 6C.
Xc (t, n = 1) = + cos (2 * pi * f * t) * w (t)
Xc (t, n = 2) = + sin (2 * pi * f * t) * w (t)
Xc (t, n = 3) =-cos (2 * pi * f * t) * w (t)
Xc (t, n = 4) =-sin (2 * pi * f * t) * w (t)

And for Xd that uses a term to delay the phase, as can be seen in FIG.
Xd (t, n = 1) = + cos (2 * pi * f * t) * w (t)
Xd (t, n = 2) =-sin (2 * pi * f * t) * w (t)
Xd (t, n = 3) =-cos (2 * pi * f * t) * w (t)
Xd (t, n = 4) = + sin (2 * pi * f * t) * w (t)
It becomes.

To illustrate this particular embodiment, each of the four transmit beam sequences receives four beams per transmission simultaneously, as shown in FIG. The following equation corresponds to the enclosed group 700 of receive lines for transmit Xa.
RT _XA@2.5 = a * X _A1 R ₄ + b * X _A2 R ₃ + c * X _A3 R ₂ + d * X _A4 R ₁

Since there are more simultaneous transmit beams than the previous embodiment, there are some additional constraints on the selection of the a, b, c, d coefficients.
Constraint 1: Total coherent energy from a + b + c + d = 1 Xa Constraint 2: Exclusion of energy from a-b + c-d = 0 Xb Constraint 3: a + jb-c -jd = 0 Xc Energy Exclusion Constraint 4: a -jb-c + jd = 0 Energy Exclusion from Xd

  “J” indicates an imaginary number (sqrt (−1)) and corresponds to a 90 ° phase shift with respect to transmissions Xc and Xd.

Solving for a, b, c, d, a very simple result,
a = b = c = d = 0.25
Is obtained.

  For those skilled in the art, it is easy to find similar sets of coefficients for other transmissions Xb, Xc and Xd.

  FIG. 5B shows the use of a two-dimensional matrix transducer 530 to scan the volume using four transmit beams at the same time. For matrix transducers, it is desirable to use fully sampled apertures (all of the elements are electrically active) for improved image quality and sensitivity. This is compared to a sparse array that connects only a small percentage of the elements. A fully sampled array can be achieved by using a microbeamformer installed in the housing of the matrix transducer. See US Pat. Nos. 5,997,479 and 6,126,602, which are incorporated herein by reference. Each microbeamformer appropriately beamforms a small subset of elements (called patches). As currently known to those skilled in the art, the use of microbeamformers is not compatible with simultaneous transmit beams and the present invention. This is because each patch or group of elements is limited to a single steer angle for both transmission and reception. This is because the use of multiple transmissions that are spatially separated and may not be located at the same place is implicitly included in the present invention.

  Therefore, it is a more inventive aspect of the present invention to allow simultaneous transmit beams to be used with matrix transducers using microbeamformers. One inventive element replicates one microbeamforming electronics for each simultaneous transmit beam. For example, if two beams are transmitted simultaneously, there are two microbeamformers per patch (per group of elements). Each microbeamformer generates a different transmit wave field that is combined with transmit wave fields from other microbeamformers associated with one patch and amplified to transmit sound waves into the body. To drive the patch element (see FIG. 8A). In addition, for reception, the shared patch element converts the returning sound wave into an electrical signal that is amplified and transmitted to N different microbeamformers. Each beamformer then delays and sums the patch echoes returning in the direction associated with the direction used during transmission (see FIG. 8b). In the general case, "N" microbeamformers are required for "N" simultaneous transmit beamlook directions.

  It is implicit in all of the above embodiments that they are designed for the “basic” mode of black and white grayscale imaging. In the basic mode, the transmission frequency is the same as the reception frequency. There is another mode of operation called Tissue Harmonic Imaging (THI) that is very common in current clinical practice of ultrasound diagnostics. In THI, harmonic frequencies are generated during transmission and propagation of the transmitted waveform. These harmonics (in many cases, second harmonics) are selectively separated using a bandpass filter and received. For example, the transmission waveform is centered on 2.5 MHz, and the reception filter is set to 5.0 MHz in order to selectively receive a desired second harmonic.

  In THI, it is necessary to control the transmission so that the desired phase relationship is observed during reception in order to reject cross-beam contamination from simultaneous transmission as described by the present invention. For example, in a 2x multi-beam transmission embodiment, the first beam sequence may have a common reception phase, while the second transmission set may have a received signal polarity that is switched 180 ° every other transmission. desirable. In order to achieve this 180 ° switching with respect to the received harmonics, the transmission of this sequence requires switching between 0 ° and 90 °. In other words, the transmission sequence switches between a windowed cosine burst and a windowed sine burst. In the 4x multi-beam transmission embodiment, each transmission sequence is advanced (or delayed) by 45 ° to achieve the desired 90 ° shift upon reception (relative to the second harmonic). Need).

  As known to those skilled in the art, the transmit phase shift is approximately 1 / H of the desired phase shift observed during reception ("H" is the received harmonic). It is also known to those skilled in the art that this phase relationship is not necessarily accurate and may need to be finely adjusted based on experimental measurements.

  In a preferred embodiment, the data processing unit can be an FPGA (Field Programmable Gate Array) or an ASIC (Application Specific IC). The processing can be performed using a DSP (Digital Signal Processing Unit) or other computing unit. In the preferred embodiment, two transceivers are used with one of the transmit beams switching between 0 ° and 180 ° phases. In other embodiments, more than two ultrasonic transmitters are used and the transmit beams are transmitted at 0 °, 90 °, 180 ° and 270 ° phases. In yet another embodiment, one beam is always in phase (0 °), one beam advances in increments of +90, one beam advances in increments of -90, and one beam is 0 ° And between 180 ° and 180 °.

  Without departing from the spirit and scope of the present invention, those skilled in the art can devise variations, modifications and other embodiments of what is described herein. Accordingly, the present invention is not limited only by the above description.

Claims (21)

A method for separating ultrasonic transmit beams and reducing cross transmit beam interference in a multi-beam system, comprising:
Performing a first transmission event by simultaneously transmitting at least two multiple ultrasound beams to independent spatial locations, wherein each of the transmitted at least two ultrasound beams generates an echo return;
Generate a sequence of outgoing events over a period of time,
Applying a phase factor to each of the at least two ultrasound beams transmitted in each transmission event;
At each successive transmission event, the phase factor is modulated by a unique amount for each transmitted ultrasound beam, the energy from the desired transmitted ultrasound beam is constructively added, and the remaining transmitted A method in which the echo returns from two or more transmission events are combined by destructively hindering the energy from the transmitted ultrasound beam.   The number of transmitted ultrasonic beams is equal to two transmitted ultrasonic beams per transmission event, and the phase factor is {+1 +1 +1... For one of the transmitted ultrasonic beams. ..}, and {+1 -1 +1 -1 ...} with respect to the other transmitted ultrasound beam.   The method of claim 1, wherein the independent spatial location is defined in degrees associated with one of a phased array sector and a curved linear array transformer.   The method of claim 1, wherein the independent spatial locations are offset in a lateral distance associated with a linear transducer.   The method of claim 1, wherein the independent spatial locations correspond to different transmit depths of focus.   The method of claim 1, wherein the successive transmission events sequentially scan one of a two-dimensional image and a three-dimensional volume.   The method of claim 1, wherein the at least two transmitted ultrasound beams are separated after receive beamforming at a summing node.   The method of claim 7, further comprising using parallel processing during receive beamforming to generate one or more receive beams for each of the at least two transmitted ultrasound beams.   Each of the received beams has a unique set of coefficients that are used to synthesize energy from successive transmit events, the energy from the desired transmitted ultrasound beam is constructively added, and other unwanted The method of claim 8, wherein energy from the transmitted ultrasound beam is disruptively disrupted.   The method of claim 1, wherein the multi-beam system includes an ultrasonic transducer that utilizes microbeamforming electronics.   The microbeamforming electronics beamform at least one patch and the in-group processor for each patch is replicated N times for each of N spatially independent transmitted ultrasound beams. The method according to claim 10.   The method of claim 1, wherein the phase factor modulation can be approximated using a time delay in at least one of transmission and reception.   The method of claim 1, wherein the phase coefficient is modulated using tissue harmonic imaging.   The tissue harmonic imaging has at least two harmonic components, the phase coefficient modulation amount applied to the transmit beam is essentially equally divided, and the phase coefficient observed at 2xRF during reception is the at least 2 14. The method of claim 13, wherein the method is effectively doubled through nonlinear wave propagation associated with the second of the two harmonics.   For the Mth harmonic component of the transmitted waveform, the amount of phase coefficient modulation applied to the transmit beam is essentially equally divided and observed at the Mth received harmonic MxFxmit during reception. 14. The method of claim 13, wherein the phase factor is effectively doubled through nonlinear wave propagation associated with the second harmonic of tissue harmonic imaging. A method that enables a high frame rate in ultrasound imaging,
A matrix array ultrasonic transducer with one or more microbeamformers is used to transmit multiple ultrasonic beams simultaneously, the matrix transducer being used to perform some aspects of beamforming. Independent and separately transmitted ultrasonic waves having a two-dimensional array of ultrasonic elements including electronic circuits in a housing, wherein the electronic circuits in the transducer housing are beamformed at independent spatial locations How to support the beam. Generating a sequence of transmit events over a period of time, each transmit event including transmitting multiple ultrasound beams simultaneously at independent spatial locations, each transmitted ultrasound beam generating an echo return;
Applying a phase factor to each of the transmitted ultrasound beams at each transmission event;
In each successive transmission event, the phase coefficient is modulated by a unique amount for each transmitted ultrasound beam, and the echo return from more than one transmission event is derived from the desired transmitted ultrasound beam. The method of claim 16, wherein the energy is combined constructively and destructively hindering energy from the remaining transmitted ultrasound beam.   17. The method of claim 16, wherein at least two microbeamformers that transmit the beam simultaneously constitute a patch.   The method of claim 16, wherein each microbeamformer generates a different transmit wave field and the different transmit wave fields of the microbeamformer in a patch can be combined.   The method of claim 16, wherein the intra-group processor for each patch is replicated N times for each of the spatially independent transmitted ultrasound beams.   The method of claim 16, wherein the phase factor modulation can be approximated using a time delay in at least one of transmission and reception.

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